Comparative evaluation of pectolytic and proteolytic enzyme production by free and immobilized cells of some strains of the phytopathogenic Erwinia chrysanthemi

Whole cells of the phytopathogenic Erwinia chrysanthemi strains were immobilized in k-carrageenan and grown in high-calcium Xanthomonas campestris medium containing sodium polypectate as carbon source. All the strains used survived immobilization into k-carrageenan beads. Immobilized E. chrysanthemi strains displayed higher pectolytic and proteolytic enzyme activities than free cells in liquid suspension. Carrageenan immobilization techniques could provide a system to mimic the conditions of E. chrysanthemi cells in the infected plant tissue. This could prompt a thorough study of the factors governing the biosynthesis of virulence factors by this bacterium. Journal of Industrial Microbiology & Biotechnology (2001) 27, 215–219. Received 04 April 2001/ Accepted in revised form 12 June 2001     

Light intensity regulates growth and reproduction of a snail grazer (Gyraulus chinensis) through changes in the quality and biomass of stream periphyton

1. The light : nutrient hypothesis (LNH) proposes that herbivore growth rates are maximised at intermediate light‐to‐nutrient ratios. A reduction to light intensity (i.e. decreased light‐to‐nutrient ratio) should lead to reduced food availability for herbivores while excessive light intensity in oligotrophic environments (i.e. increased light‐to‐nutrient ratios) should increase the C : N and C : P ratios of producers. However, this hypothesis has not yet been supported by studies on stream ecosystems. 2. We tested the LNH by experimental application of controlled natural gradients in light intensity to oligotrophic laboratory channels that included periphyton and the freshwater snail Gyraulus chinensis. 3. The results in this oligotrophic environment indicate that light regulated the flow of matter between trophic levels and grazer reproduction by controlling C : P ratios of the producers.     

The ecology and agronomy of Miscanthus sinensis, a species important to bioenergy crop development, in its native range in Japan: a review

Among several candidate perennial taxa, Miscanthus × giganteus has been evaluated and promoted as a promising bioenergy crop. Owing to several limitations, however, of the sterile hybrid, both at the taxon and agronomic production levels, other options need to be explored to not only improve M . × giganteus , which was originally collected in Japan, but to also consider the development of other members of its genus, including Miscanthus sinensis , as bioenergy crops. Indeed, there is likely much to be learned and applied to Miscanthus as a bioenergy crop from the long history of intensive interaction between humans and M. sinensis in Japan, which in some regions of the country spans several thousand years. Combined with its high amount of genetic variation, stress tolerance, biotic interactions with fauna, and function as a keystone species in diverse grasslands and other ecosystems within its native range, the unique and extensive management of M. sinensis in Japan as a forage grass and building material provides agronomists, agroecologists, and plant breeders with the capability of better understanding this species in terms of potential contribution to bioenergy crop development. Moreover, the studies described in this review may serve as a platform for future research of Miscanthus as a bioenergy crop in other parts of the world.     

Aboveground plant biomass,carbon, and nitrogen dynamics before and after burning in a seminatural grassland of Miscanthus sinensis in Kumamoto,Japan

Although fire has been used for several thousand years to maintain Miscanthus sinensis grasslands in Japan, there is little information about the nutrient dynamics in these ecosystems immediately after burning. We investigated the loss of aboveground biomass; carbon (C) and nitrogen (N) dynamics; surface soil C change before and after burning; and carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) fluxes 2 h after burning in a M. sinensis grassland in Kumamoto, Japan. We calculated average C and N accumulation rates within the soil profile over the past 7300 years, which were 58.0 kg C ha^?1 yr^?1 and 2.60 kg N ha^?1 yr^?1, respectively. After burning, 98% of aboveground biomass and litter were consumed. Carbon remaining on the field, however, was 102 kg C ha^?1. We found at least 43% of C was possibly lost due to decomposition. However, remaining C, which contained ash and charcoal, appeared to contribute to C accumulation in soil. There was no difference in the amount of 0–5 cm surface soil C before and after burning. The amount of remaining litter on the soil surface indicated burning appeared not to have caused a reduction in soil C nor did it negatively impact the sub‐surface vegetative crown of M. sinensis. Also, nearly 50 kg N ha^?1 of total aboveground biomass and litter N was lost due to burning. Compared with before the burning event, postburning CO₂ and CH₄ fluxes from soil appeared not to be directly affected by burning. However, it appears the short time span of measurements of N₂O flux after burning sufficiently characterized the pattern of increasing N₂O fluxes immediately after burning. These findings indicate burning did not cause significant reductions in soil C nor did it result in elevated CO₂ and CH₄ emissions from the soil relative to before the burning event.